Interaction
Between Genetic Background and Early Rearing Conditions on the
Development of Social Behavior in Mice

This
study examined the interaction of early rearing environment and genetic
background on the development of social behaviors in mice. Most
research on the effects of early experience on development focuses on
the timing and type of early perturbations. To date comparatively
little research has focused on the role of genetic variation in how the
nervous system interprets a particular type of experience. This study
examines how genetic makeup might produce different responses, in adult
mice, to early experiences. The study examined the response of several
different strains of mice to varying periods of handling. Replicating
earlier studies in rats, this experiment showed that animals handled
daily for a relatively short period of time as infants show less
response to stress as adults, compared to normal animals and animals
handled daily for a very long period of time.

These
experiments are the first step in laying the groundwork for significant
research in the genetic contribution to behavioral differences.
Replicating this research in the mouse will allow scientists to conduct
similar studies with strains of mice that are known to have distinct
genetic patterns underlying specific behavioral traits such as anxiety
or heightened reactivity to stress. Such genetic patterns are not yet
well established in rats. Knowing the genetic differences in these
strains, combined with examining brain differences in animals with
different responses to early experiences, will allow scientists to
hypothesize about the way experience and genetic makeup interact to
produce particular behavioral outcomes.